The research in this proposal is projected into 2 divisions: 1. Psoriasis biology in which tissue culture, radiolabeling, ultrastructural and time lapse photographic techniques will be employed to determine whether the proliferative and functional derangements in psoriasis represent permanent abnormalities of the epidermis. A variety of animal model systems (lizard skin, mouse vagina), which bear certain similarities to the epidermis in psoriasis will also be used in analysis of controls of epithelial behavior. The role of cell communication, the cell surface, and feedback loops will be determined insofar as they may control proliferation within the epidermis. Possible roles for nonepidermal controls such as mesenchymal, hormonal and other chemical factors will be studied. 2. Mechanisms of psoriagenesis in which the nature of skin trauma requisite to induce a lesion of psoriasis will be sought.